Manufacture and production of artificial threads, filaments, and the like



Patented Sept. 25, 1945 MANUFACTURE AND PRODUCTION OF ARTI- FICIAL THREADS, FILAMENTS, AND THE LIKE Robert Louis Wormell, Coventry, and Claude Leonard Knight, Rugby, England, asslgnors to Courtaulds Limited, London, England, a British company Claims.

This invention relates to the manufacture and production of artificial threads, filaments, fibres and the like, hereinafter referred to as threads, from solutions of caseins, for example animal casein from milk vegetable seed proteins such as those obtained from soya beans or peanuts.

It is well kno n to produce threads from caseins by extrudi g an alkaline solution of the casein into a coagulating bath and subjecting the resultant thread to a treatment known as hardening," which comprises passing the thread through one or more baths comprising aqueous solutions of one or more "suitable substances such as formaldehyde and metallic salts such as aluminium. The threads obtained are insoluble in cold water but on placing in boiling water or hot dilute acid the threads become plastic and tend to stick together, or even to dissolve.

We have now found that casein threads of improved resistance to attack by boiling wateror hot dilute acid can be obtained by treating the threads with a solution containing formaldehyde, alkali metal sulphate and sufilcient sulphuric acid to convert at, least a large proportion of the sulphate into bisulphate.

The said treatment may be applied to the casein threads either before, during or after the hardening treatment. The'tre'ating bath used No Drawing. Application April 22, 1942,.sem1

\ No. 440,116. In Great Britain May 27,1941

I In carrying out the process of the presentinvention it is desirable to use a large quantity of liquid which is of high specific gravity by using a. sinking device such as a heavy cage or wire frame of non-corrodible material.

liquor is preferably circulated through the according to the present inventionfcan be prepared by adding formaldehyde to the solution produced by dissolving sodium bisulphate in water. Instead of sodium bisulphate, sodium sulphate and sulphuric acid can be added separately, whereby it is unnecessary that the quantity of sulphuric acid should be exactly that required to convert sodium sulphate into bisulphate, since either a somewhat smaller or larger quantity can be employed.

This process can be carried out at any suitable temperature but we prefer to commence the treatment at a low temperature so as to increase the resistance of the threads and then subsequent treatments can be carried out under more drastic conditions without damaging the threads.

The alkali metal bisulphate used is preferably sodium bisulphate and as stated above the treating liquor can be made up by mixing'sodium sulphate and sulphuric acid in amounts corresponding to sodium bisulphate and then adding formaldehyde. If desired, aluminium salts may be added to the treating bath, but if the threads have already been hardened with an aluminium' salt this is not necessary. Bleaching agents such the treating bath,

threads. After the treatment the threads are washed and dried.

I The threads treated according to the present invention exhibit a high resistance to boiling liquids and even after boiling for thirty minutes with two per cent sulphuric acid are found to"- retain a larger part of their combined formaldehyde than do the untreated threads under the same conditions. The threads alsoacquire an increased resistance to shrinkage in steam.

The following examples illustrate the nature of the present invention, although the invention is not restricted to these examples.

Example 1 10 kilograms of freshly spun casein threads are hardened in a bath containing per litre of solution 606 grams of aluminium sulphate A12(SO4)3.18H2O, 40 grams of formaldehyde and 131 grams of sodium carbonate for six hours at room tern-i peratiue. The threads are centrifuged, washed and placed in 20 parts by volume of a bath containing per litre of solution:

for 24 hours at 25 centigrade. They are then.

centrifuged, washed and thereafter soaked for six hours at room temperature in 0.75 per cent sul- 'phuric acid. After centrifuging, the threads are are given a soft finish by treating with a solution containing 0.25 per cent of Turkey red oil and 0.25 per cent of sodium bicarbonate and finally dried. They have a high wet strength and are The treating resistant to boiling in a 2 per cent sulphuric acid solution.

Example ,2

24 kilograms of freshly spun casein threads are hardened for 20 hours at room temperature in a bath prepared from 640 grams of aluminium sulphate A12(SO4)3.18H2O, 40 grams of formaldehyde and 131 grams of sodium carbonate for each litre of the solution. The threads are centrifuged, washed and placed for 48 hours at 30 centigrade in 20 parts by volume of a bath containing per litre of solution 215 grams of sulphuric acid, 346 grams of anhydrous sodium sulphate, 9 grams of aluminium sulphate and 63 grams of formaldehyde. After centrifuging and washing the threads are placed for. 20 minutes in a 0.25 per cent solution of sodium bicarbonate, they are then washed and dried.

Example 3 A 15 per cent solution of soya bean casein dissolved in a 1.4 per cent solution of caustic soda is extruded from a jet into a coagulating bath containing per litre 360 grams of sodium'sulphate and 90 grams of sulphuric acid. The threads obtained are hardened for 42 hours at 45 centigrade in a bath containing per litre Example 4 5 kilograms of freshly extruded casein threads are treated at room temperature for 20 hours in a hardening bath containing 363 grams of aluminium sulphate, 38 grams of formaldehyde and 93 grams of sodium carbonate per litre. The threads are centrifuged, washed and treated for 48 hours at centigrade in a bath containing per litre 252 grams of sulphuric acid, 375 grams of sodium sulphate, 62 grams of formaldehyde and 7 grams of aluminium sulphate. After centrifuging, washing and treating for 20' minutes in a 0.25 per cent solution of sodium bicarbonate, the threads are washed and treated in a bath of the following composition per litre:

Grams Aluminium sulphate 31 Sulphuric acid 181 Sodium sulphate 319 Formaldehyde 56.

The bath is maintained at 52 centigrade for 16 hours. The threads are washed and dried. After boiling with a 2 per cent solution of sulphuric acid for 30 minutes the threads still contained 1.15 per cent of combined formaldehyde.

What we claim is:

1. A process for improving the resistance of casein threadsto attack by boiling aqueous liquids which consists in treating the said casein threads in a bath containing formaldehyde. alkali metal sulphate and sulficient sulphuric acid to convert at least a large proportion of the sul phate into bisulphate the sulphuric acid content of the bath being equivalent to a normality of the order of about 3.7 to about 5.1, and then while avoiding any appreciable increase in concentration of the sulphuric acid, in contact with the threads, immediately after said treatment washing and drying the said threads.

2. A process for improving the resistance of casein threads to attack by boiling aqueous liquids which consists in treating the said casein threads in a bath containing formaldehyde, alkali metal sulphate and sufficient sulphuric acid to convert at least a large proportion of the sulphate into bisulphate and an aluminium salt the sulphuric acid content of the bath being equivalent toa normality of the order of about 3.7 to about 5.1,.and then while avoiding any appreciable in crease in concentration of the sulphuric acid, in contact with the threads, immediately after sai treatment washing and drying the said threads.

3. A process for improving the resistance of casein threads to attack by boiling aqueous liq uids which consists in treating the said casein threads in a bath containing formaldehyde, alkali metal sulphate and sufllclent sulphuric acid to convert at least a large proportion of the sulphate into bisulphate, the sulphuric acid content of the bath being equivalent to a normality of the order of about 3.7 to about 5.1, and then while avoiding any appreciable increase in con centration of the sulphuric acid in contact with the threads, immediately after said treatment washing, and then treating the threads in a hardening bath.

4. A process for improving the resistance of casein threads to attack by boiling aqueous liq uids which consists in treating the hardened casein threads in a bath containing formaldehyde, alkali metal sulphate and sufflcient sulphuric acid to convert at least a large proportion of the sulphate into bisulphate, the sulphuric acid content of the bath being equivalent to a normality of the order of about 3.7 to about 5.1, and then while avoiding any appreciable increase in concentration of the sulphuric acid, in contact with the threads, immediately after said treatment washing and drying the said threads.

5. A process for improving the resistance of casein threads to attack by boiling aqueous liquids which consists in treating the hardened casein threads in a bath containing formaldehyde, alkali metal sulphate and sufiicient sulphuric acid to convert at least a large proportion of the sulphate into bisulphate the sulphuric acid content of the bath being equivalent to a normality of the order of about 3.7 to about 5.1. and then while avoiding any appreciable increase in concentration of the sulphuric acid in contact with the threads, immediately after said treat ment washing, and then subjecting the threads to a further treatment in a hardening bath.

ROBERT LOUIS WORMELL. CLAUDE LEONARD KNIGHT; 

